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Old 01-15-2013, 10:36 PM   #41
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I wanted to see the efficiency of SlickAutos dive planes APR Carbon Fiber 3D Canards $285 or $355 | Slick Auto and how does the splitter effect it (with the distance between them)
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Old 01-15-2013, 11:20 PM   #42
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shouldn't affect the splitter, they're doing 2 opposite things.
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Old 01-16-2013, 01:15 AM   #43
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Quote:
Originally Posted by ThePass View Post
How do so many aero theads divert into trying to explain to someone that hood risers are utterly useless? By how many times its been gone over by now, I'm surprised it even comes up any more.

-Ryan
I'm well aware of why they dont work to lower water temps. I never said they did. Do people even read posts?
I've seen tests demonstrating lower engine bay temps because of them.
In a drift day you tend to spend a lot of time waiting in line with your car running and your bonnet down. There are people on here who are into drifting, I'm not really one of them, but it may help them.

The thing that always impresses me about this forum is the knowledge. And I think its better for people to know what they do and what they dont instead of just saying "They're ****."
I havent put enough research/thought into heat sheilds vs ventilation in this niche application to discuss it. And I dont think this is the appropriate place to do so.
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Old 01-16-2013, 03:21 AM   #44
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Quote:
Originally Posted by Vilko View Post
I'm well aware of why they dont work to lower water temps. I never said they did. Do people even read posts?
I've seen tests demonstrating lower engine bay temps because of them.
In a drift day you tend to spend a lot of time waiting in line with your car running and your bonnet down. There are people on here who are into drifting, I'm not really one of them, but it may help them.

The thing that always impresses me about this forum is the knowledge. And I think its better for people to know what they do and what they dont instead of just saying "They're ****."
I havent put enough research/thought into heat sheilds vs ventilation in this niche application to discuss it. And I dont think this is the appropriate place to do so.
Nobody ******* cares what drifters are doing.
This thread is about a guy building an undertray for the purpose of GOING FASTER. Why in the **** are you talking about motherfucking drifting?! Hood risers make sense in drifting because hood risers are retarded and drifting is too. Being retarded has nothing to do with this thread.

Seriously, go away. I hate you.
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Old 01-16-2013, 03:32 AM   #45
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Well I lol'd.

What Mr Boogie said.

Let me hit you with an idea, if this was air cooled VW drift forum, people here would give maybe even half a **** about engine bay temperature, but its water cooled mazda performance forum, and here no one gives a dam about how warm the cam cover is, sorry bruh.

Dann
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Old 01-16-2013, 04:40 AM   #46
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Sorry, but if the ambient heat in your engine bay is too much for your car to handle, stay out of the kitchen.
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Old 01-16-2013, 04:51 AM   #47
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But what about my turbo manifold? Im not sure it can handle the hot air on it, and thats an expensive part!?

Dann
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Old 01-16-2013, 09:51 AM   #48
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Originally Posted by motormechanic View Post
shouldn't affect the splitter, they're doing 2 opposite things.
I wasn't talking about the canards affecting the splitter, I was talking the complete opposite. On a wing and most aero surfaces the top part of the wing pushes down about 1/3 of the force. 2/3 of it comes from the bottom being sucked down. So my question was if the canard was to close to the splitter would it be less effective?
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Old 01-16-2013, 10:00 AM   #49
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Is there a way to lessen the low pressure area on top of the roof, but I;m guessing not since that is high speed air. Is that a small hint of blue on top of the hood just in front of the budge?
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Old 01-16-2013, 11:11 AM   #50
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Originally Posted by 1993ka24det View Post
I wasn't talking about the canards affecting the splitter, I was talking the complete opposite. On a wing and most aero surfaces the top part of the wing pushes down about 1/3 of the force. 2/3 of it comes from the bottom being sucked down. So my question was if the canard was to close to the splitter would it be less effective?
A canard is not profiled like a wing, however. The purpose of the canard is to create vortices along the side of the car, downforce gains are minimal from canards and are mainly used for balancing F/R bias.
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Old 01-16-2013, 11:12 AM   #51
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Quote:
Originally Posted by 1993ka24det View Post
Is there a way to lessen the low pressure area on top of the roof, but I;m guessing not since that is high speed air. Is that a small hint of blue on top of the hood just in front of the budge?
Yes there is a hint of blue right where the hood opens and right in front of the bulge.
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Old 01-16-2013, 12:15 PM   #52
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Race prep subsection, race prep thread. We have a BS subsection just perfect for drifting talk.

Those canards will increase drag. Flares that gently direct air out past the fronts of the wheels do not, but rather smooth the flow that would otherwise strike the tire directly and deflect into the wheel well.

As for the low pressure area over the roof, low pressure is created by the faster airflow over the surface (see mathematician Daniel Bernoulli).
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Old 01-16-2013, 03:30 PM   #53
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As for the low pressure area over the roof, low pressure is created by the faster airflow over the surface. [/QUOTE]

Yep and i was thinking is there a way to slow the air on the roof with out to much drag or turbulence, maybe a gurney flap
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Old 01-16-2013, 03:54 PM   #54
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Quote:
Originally Posted by 1993ka24det View Post
Is there a way to lessen the low pressure area on top of the roof, but I;m guessing not since that is high speed air.
You can think of increasing the radius of the roof, making it less of a high speed area.
Removing the windshield+roof is one way
Fastback is another, less drastic way (but mostly even out the flow/pressure over the roof+trunk area, in my personal simplistic analysis).
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Old 01-16-2013, 08:39 PM   #55
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Originally Posted by 1993ka24det View Post
I wanted to see the efficiency of SlickAutos dive planes APR Carbon Fiber 3D Canards $285 or $355 | Slick Auto and how does the splitter effect it (with the distance between them)
PM me specifics if you want to set up an analysis.

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You can think of increasing the radius of the roof, making it less of a high speed area.
Removing the windshield+roof is one way
Fastback is another, less drastic way (but mostly even out the flow/pressure over the roof+trunk area, in my personal simplistic analysis).
Fastbacks still create a lot of lift and most of the time more than a coupe, because they have a much greater area where the lower pressure is effecting. Fastbacks will have lower drag however.
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Old 01-17-2013, 12:40 PM   #56
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Note: the rear lip spoiler's function is to reduce the speed of the air above the trunk surface to reduce the lift on the rear of the car, and not actually to direct air upward and force the rear of the car downward as a dive plane would.

Disturbing the high speed laminar flow over the roof surface will indeed reduce lift, but will often create huge amounts of drag. If vortex generators were employed at the leading edge of the roof you would see this. Vortex generators at the rear of the roof, however, have been shown to be useful in reduction of the separation of the boundary layer from the rear glass and trunk lid surface and creating more effective use of spoilers and wings mounted at the rear of the car. But this thread is about flat underbodies. /threadjack
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Old 01-17-2013, 01:50 PM   #57
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But this thread is about flat underbodies. /threadjack
Not entirely off topic. The spoiler cleans up the airflow at the rear of the car and increases mass airflow underneath the car. These CFD plots are of a modern nascar-type car, without a flat underbody, and they showed 550lbs of downforce at 112mph. With a flat underbody, mass flow underneath the car would be made that much more effective, and the benefits of the spoiler would increase correspondingly. The combination of the two is much much more effective than either by itself.

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Old 01-23-2013, 05:03 AM   #58
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I was going to show just "plucas" until it is done, but I guess I will show all of you now what my plans are for the under tray. This car is a Porsche race car I found on google, but don't know yet until after some testing.



I know this was brought up before about the heat being trapped in the trani tunnel. I ordered a digital wind meter and will be placed in the tunnel in numerous places. The car will be driven at 60 mph, 80 mph and at 100 mph to see the ratio of speed of air moving in the tunnel.

Right now I am not as worried about heat since it gets no hotter than 50 deg F out side and that there is a 1" opening between the flat panel and the steering rack. I do not want to also just start cutting holes for NACA ducts in the floor in places where there shouldn't have been.
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Old 01-23-2013, 12:29 PM   #59
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Keep in mind that Porsche obviously has no heat from engine bay, turbo, exhaust, etc. in the front 3/4 of the car - so managing heat with an underbody is incredibly simpler for them.

Ambient temp is really not a significant issue - your exhaust gasses are 1500 degrees either way, so whether it's 40* outside or 100*, if the heat in the transmission tunnel for example is going to overheat components, it will probably still happen. Since you're making yours out of all aluminum, you obviously don't have to worry about damaging the undertray itself with heat, but the general consensus seems to be that the differential relies a lot on air passing around it to cool it, so that's probably the most important area to either supply air to, or install a cooler for.

-Ryan
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Old 01-23-2013, 02:49 PM   #60
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Quote:
Originally Posted by plucas View Post
This. Higher pressure builds at the top of the hood at the windshield. Higher pressure areas are not where you should try to exit air; it is where you should have inlets. Looking below you can see the science...


Hmmm, have the same thing with the roof down? :-) Guess you'd have to at least model seats and roll bar.... Once I made an amplifier cooler for my biggie stereo by running shop-van tubing in and out of the trunk. Seemed to work well though later I did it right.
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